As part of her role playing Janet Leigh in the upcoming drama Hitchcock, ScarJo had to recreate the iconic shower scene in Psycho in which Marion Crane is stabbed to death by a cross-dressing Norman Bates.

"She was really good," director Sacha Gervasi told me last night at the world premiere of the movie at the AFI Fest presented by Audi Film Festival in Hollywood. "She is a real screamer."

Gervasi said they never rehearsed the scream. "We just did it," he said. "That's the great thing about Scarlett—she's all chilled out and then you call, 'Action!' and she just goes nuts…She gave everything."

The film (opening in limited release on Nov. 23) centers around Alfred Hitchcock (Anthony Hopkins) and his wife Alma (Helen Mirren) and their struggle to make Psycho.

"The guy just morphed into another person completely," said Richard Portnow, who plays Barney Balaban, the head of Paramount Pictures who fought Hitchcock's decision to make a horror movie. "He wore a fat suit. They shaved his head and gave him a fake nose and jowls. He had the waddle and sounded like him—but just enough. He didn't mimic the guy."

The Hitchcock premiere served as the kickoff to this year's AFI Fest presented by Audi Film Festival. Also expected to walk the fest's red carpet during the next week are Kristen Stewart for On the Road, Bradley Cooper for Silver Linings Playbook and Ewan McGregor for his upcoming tsunami drama, The Impossible.

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